Pheromonal enrichment in the zoo: An empirical approach with Asian elephants (Elephas maximus)

The Scent Enriched Primate

Zoos worldwide play an important role in both in situ and ex situ conservation via efforts such as providing breeding programmes and reintroductions into the wild. Zoo populations are crucial as a buffer against extinction. However, a mismatch between the wild and zoo environments can lead to psychological as well as physiological health issues, such as stress, boredom, diabetes, and obesity. These problems, in turn, can impact the reproductive success of individuals. Consequently, some primate species have reduced breeding success when housed in zoos compared to their wild counterparts. To prevent the onset of behavioural, physiological, and cognitive negative effects and to continually improve the welfare of their animals, zoos widely implement different types of environmental enrichment. There are many forms enrichment can take, such as feeding, puzzles and training, but sensory enrichments, including implementing the use of scents, are currently understudied. Scent enrichments are less utilized despite multiple research studies showing that they may have positive effects on welfare for zoo-housed animal species, including non-human primates. Despite being traditionally considered to be microsmatic, various lines of evidence suggest that olfaction plays a larger role in primates than previously thought. This review therefore focuses on scent-based enrichment and the specifics of captive primates.

Investigating Unused Tools for the Animal Behavioral Diversity Toolkit

Behavioral diversity is a commonly used tool used to quantify the richness and evenness of animal behaviors and assess the effect of variables that may impact an animal's quality of life. The indices used in behavioral diversity research, and the study subjects, have not been formally reviewed. This paper aims to identify which indices are being used in behavioral diversity research, and under which scenarios, and uncover novel indices from other disciplines that could be applied to behavioral diversity. To investigate the techniques and species investigated in behavioral diversity literature, a Web of Science literature search was conducted. Two methods: behavioral richness and the Shannon-Wiener index, were the most frequently used indices, whereas the Behavioral Variability index featured rarely. While a range of species appeared in the behavioral literature, mammals were the most frequently studied Class, whereas amphibians did not feature in any papers. There are several diversity indices which did not feature in behavioral diversity including Simpson's index, and Chao. Such indices could be used to better understand animal behavioral study outputs or be used to estimate the number of 'unobserved' behaviors that an animal may express. Future studies could therefore extend beyond the Shannon-Wiener and richness indices.

The Chemical Ecology of Elephants: 21st Century Additions to Our Understanding and Future Outlooks

Chemical signals are the oldest and most ubiquitous means of mediating intra- and interspecific interactions. The three extant species of elephants, the Asian elephant and the two African species, savanna and forest share sociobiological patterns in which chemical signals play a vital role. Elephants emit secretions and excretions and display behaviors that reveal the importance of odors in their interactions. In this review, we begin with a brief introduction of research in elephant chemical ecology leading up to the 21st century, and then we summarize the body of work that has built upon it and occurred in the last c. 20 years. The 21st century has expanded our understanding on elephant chemical ecology, revealing their use of odors to detect potential threats and make dietary choices. Furthermore, complementary in situ and ex situ studies have allowed the careful observations of captive elephants to be extended to fieldwork involving their wild counterparts. While important advances have been made in the 21st century, further work should investigate the roles of chemical signaling in elephants and how these signals interact with other sensory modalities. All three elephant species are threatened with extinction, and we suggest that chemical ecology can be applied for targeted conservation efforts.